. Text-book of normal histology: including an account of the development of the tissues and of the organs. nation. Within the epidermis the duct loses itsdistinct walls, the final turns of its spiral, corkscrew-like coursebeing bounded by the horny plates of the epidermis. In cases the sweat-glands open into the upper part of thehair-follicles, but, as a rule, they reach the iree surface by enteringthe epidermis in the depressions between the papillae of thecorium. The terminal secretory segment of the gland-tube, usuallysingle, although sometimes branched, is convoluted to form
. Text-book of normal histology: including an account of the development of the tissues and of the organs. nation. Within the epidermis the duct loses itsdistinct walls, the final turns of its spiral, corkscrew-like coursebeing bounded by the horny plates of the epidermis. In cases the sweat-glands open into the upper part of thehair-follicles, but, as a rule, they reach the iree surface by enteringthe epidermis in the depressions between the papillae of thecorium. The terminal secretory segment of the gland-tube, usuallysingle, although sometimes branched, is convoluted to form the char-acteristic coils, which can be seen often with the unaided eye asreddish-yellow spherical masses. The columnar secreting cells(10-20 ;JL in height) present a single layer of elements whose pro-toplasm is very finely granular and sometimes contains fatty gran-ules, as well as yellow or brown particles ; these latter are espe-cially evident in the ceruminous glands of the external ear, the axillaryand the mammary areolar glands. The nuclei of the secreting cells THE SKIN AND ITS APPENDAGES. 275. are eccentrically placed, while the border of the cells next the lumenpresents a thickened edge sometimes described as a cuticle. Immediately outside the epithelial cells, between these and thebasement-membrane, lies a thin layer of involuntary muscle ; Fig. 310. this tissue occurs only in the se-cretory division of the tube, andis best developed in the largerglands, where the muscle - cellsform a complete layer. The in-dividual convolutions of thetube constituting the coil are heldtogether by delicate connectivetissue, which additionally furnishesa fibrous envelope for the entiremass. The average diameter ofthe secreting portion of the glandis about 65 IJ-, of which about 30 contributed by the epitheliallining, and about half as much bythe fibrous and muscular tunics ;the remaining 20 ix represent theusual lumen. The secretion of the sweat-glands varies with the locality a
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